Field of the Invention
This invention relates to a semiconductor manufacturing apparatus and a method for cleaning the same using a cleaning gas generated by the reaction of a combustible gas and a combustion-supporting gas.
Background Art
In an LPCVD (low pressure chemical vapor deposition) apparatus, in the course of its use, a deposition film of thin film materials is inevitably formed inside its processing chamber.
The thin film materials include, for instance, silicon, silicon oxide, or silicon nitride to be deposited on a silicon wafer. Such a deposition film, when thickened, is delaminated into particles, which unfortunately contaminate the inside of the processing chamber and the wafer.
Thus, the inside of the processing chamber needs to be regularly cleaned to remove the deposition film. As a method for this cleaning, a technique of etching the deposition film by a cleaning gas containing hydrogen fluoride gas (HF) is developed. However, while the supply pipe of the cleaning gas is typically formed from stainless steel, hydrogen fluoride gas (HF) has very high corrosivity. Hence, if hydrogen fluoride gas itself is introduced into the processing chamber, it corrodes the supply pipe. Then, metal fluorides generated by corrosion flow into the processing chamber and contaminate the inside of the processing chamber and the wafer. Thus, an alternative cleaning technique is proposed in, e.g., JP-A-2008-098431(Kokai). In this technique, fluorine gas (F2) and hydrogen gas (H2) are separately introduced into the processing chamber and reacted therein to generate hydrogen fluoride gas (HF), which is used to clean the processing chamber.
However, the inventors have discovered that the inside of the processing chamber is locally damaged when it is cleaned by the method described in JP-A-2008-098431(Kokai).